Peace talks between the leftist guerrillas and the government are due to open on 27 October.

The Colombian army has killed one rebel of the National Liberation Army (ELN) and captured four others in the northern province of Casanare, authorities said on Monday (17 October). According to reports, the army has also freed two minors from the rebels in the operation.

The operation, which was launched only a few days ahead of the peace talks between the leftist guerrillas and the government, targeted the public order division and financial wings of the ELN in the northeastern department of Casanare. In the process, the head of the group's finance committee and the leader of its public order division were also detained.

A statement from the defence ministry said that the operation was meant to demolish the ELN's territory by breaking its finance and policing mechanisms, by which they extract resources from farmers, ranchers and transporters.

"At the location, soldiers discovered war materials, explosives, communications, logistics and devices with information of interest to state security agencies," the military said in a Twitter post and added that a separate operation led to the "demobilization" of 24 ELN rebels.

The peace talks between the leftist rebels and the Colombian government are due to open in the Ecuadorian capital of Quito on 27 October. The two parties have been engaged in an armed conflict for more than five decades. Monday's operation could deal a blow to the peace efforts between the rebels and President Juan Manuel Santos's government, reports say.

President Santos won the Nobel Peace Prize on 7 October for reaching a peace deal with another rebel group, the Revolutionary Armed Forces of Colombia (Farc), after years of negotiations to end a 52-year-old conflict.

On 26 September, Santos and the Farc leader Rodrigo Londono signed the historic peace accord. But, the deal, which was subject to ratification by Colombian voters in a referendum, was rejected by the people a week later.

The Farc and the government have been observing a ceasefire since 29 August.

Pablo Beltran, representative of the delegation of National Liberation Army (ELN) for formal peace talks with Colombian government, talks to the media during a news conference in Caracas on 30 March 2016Reuters